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13. Egg WhiteRenate Landig

German Team

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Task

White light appears red when it is

transmitted through a slice of boiled egg

white. Investigate and explain this

phenomenon. Find other similar examples.

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Overview

Experiments

Structure of Egg White

Theory

Rayleigh Scattering

Similar Examples

Modified Rayleigh Scattering

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Experimental Setup

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Basic Experiment

Unpolarized white light

0.15 mm solid egg white

the screen behind the slice:

spectrum with sample

without

prism

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Spectrometer

280nm: absorption maximum

Boiled egg (d=0.1mm)

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Structure of Egg White

mixture of proteins in water

protein: 20 different amino acids

unfolding through heat input

reactions between proteins

unstructured network (random coil) density fluctuations scattering

Denaturated egg white:

Liquid egg white:

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Scattering

Wave excites particles oscillation

Hertzs dipole

Scattering fields

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Derivation of E-field

P

Er

_O

2

2

dt pdtdIdtdBE 0

2EE

rE

1

ckc ==

2

(1) tiepp

0=

(2)

sinE

(3)

(4)

sin

40

2

0

r

kEE=

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Unpolarized Light

||

E

||E

||,0E

,0E

.

cos

4 0

2

||,0||r

kEE = 2

0

2

,0 sin4

r

kEE =

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Rayleigh Scattering

2

||

22EEE +=

0

22

0

2

4

2

)cos1(

4 Ir

k

I

+

=

4

42 1d

= krIP

2

EI

The radiant power of one particle:

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Extinction

xII

= e0

4

1ln

0 == x

I

I

Lambert-Beers Law:

Extinction:

nPn

I I

dI, dx

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Comparison with Experiment

800nm 350nm

expected

measured

1

1.2

0.8

1.8

1.6

2

1.4

extinc

tion

[1]

-4254m10

2 5431

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With Interference

2scatincsin2

cos

bkkrkr

rb

==

=

r

r

r

r

r

P

O

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Modified Rayleigh-Scattering

2

2i

sin

)sinsin(1de

1)(

2

2

a

ka

kbA

AaR

a

a-

==

2

Rlgh )(RII

=

( )=

cos1

4 0

2

0

||

Rr

VkEEE

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Dependence on

( )

+

=

ka

P

rIP

dsin

sinsin

2

cos11

d

2

2

2

2

2

2

(k) is only slightly dependant onk

2

1

P

)(k

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Extinction- -plot2

1.8

extinctio

n

[1]

1.4

1.6

1

1.2

0.8

-2122m10

2.5 43 54.53.5

1.8

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Similar Examples (1)

Sunset / Lunar eclipse

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Similar Examples (2)

Milk in water

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Similar Examples (3)

Polyethylene: e. g. white plastic bag

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Similar Examples (4)

Ouzo in water

without

liquid

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13. Egg WhiteRenate Landig

German Team